The present invention relates to cigarettes and other smoking articles such as cigars, pipes, and the like, which employ an electrical resistance heating element and an electrical power source to produce a tobacco-flavored smoke or aerosol.
Preferred smoking articles of the invention are capable of providing the user with the sensations of smoking (eg., smoking taste, feel, satisfaction, pleasure, and the like), by heating but not burning tobacco, without producing sidestream smoke or odor, and without producing carbon monoxide. As used herein, the term "smoking article" includes cigarettes, cigars, pipes, and the like, which use tobacco in various forms.
Many smoking articles have been proposed through the years as improvements upon, or alternatives to, smoking products which burn tobacco.
Many tobacco substitute smoking materials have been proposed, and a substantial listing of such materials can be found in U.S. Pat. No. 4,079,742 to Rainer et al. Tobacco substitute smoking materials having the tradenames Cytrel and NSM were introduced in Europe during the 1970's as partial tobacco replacements, but did not realize any long-term commercial success.
Numerous references have proposed smoking articles which generate flavored vapor and/or visible aerosol. Most of such articles have employed a combustible fuel source to provide an aerosol and/or to heat an aerosol. See, for example, the background art cited in U.S. Pat. No. 4,714,082 to Banerjee et al.
However, despite decades of interest and effort, no one had successfully developed a smoking article which provided the sensations associated with cigarette or pipe smoking, without delivering considerable quantities of incomplete combustion and pyrolysis products.
Recently, however, in European Patent Publication Nos. 174,645 and 212,234, and U.S. Pat. Nos. 4,708,151, 4,714,082, and 4,756,318, assigned to R. J. Reynolds Tobacco Co., there are described smoking articles which are capable of providing the sensations associated with cigarette and pipe smoking, by heating but not burning tobacco, and without delivering considerable quantities of incomplete combustion products. Such articles rely on the combustion of a fuel element for heat generation, resulting in the production of some combustion products.
Over the years, there have been proposed numerous smoking products, flavor generators and medicinal inhalers which utilize electrical energy to vaporize or heat a volatile material, or attempt to provide the sensations of cigarette or pipe smoking without burning tobacco.
U.S. Pat. No. 2,057,353 to Whittemore, Jr. proposed a vaporizing unit. In particular, a wick reportedly carried liquid medicament by capillary action to a point where the liquid was vaporized by an electrical resistance heating element.
U.S. Pat. No. 2,104,266 to McCormick proposed an article having a pipe bowl or cigarette holder which included a resistance coil (i) wound on an insulating and heat resisting material, and (ii) contained in an insulated chamber. Prior to use of the article, the pipe bowl was filled with tobacco or the holder was fit with a cigarette. Current then was passed through the resistance coil. Heat produced by the resistance coil was transmitted to the tobacco in the bowl or holder, resulting in the volatilization of various ingredients from the tobacco. A thermostatic switch was employed to maintain a predetermined temperature range to which the tobacco was heated.
U.S. Pat. No. 3,200,819 to Gilbert proposed a smokeless, non-tobacco cigarette having a flavor cartridge, such as a porous substrate impregnated with mentholated water. The article included a battery for powering a tube or bulb which was illuminated before assembly. The bulb was placed in a tubular liner, which was in turn located within a tube of plastic having the size, color and form of a cigarette. In use, the illuminated bulb reportedly heated the flavored air drawn through passages formed between the bulb and the tubular liner. As such, warm, moist, flavored air was delivered to the user.
French Patent Publication No. 2,128,256 to Ribot et al proposed an article for delivering denicotinized smoke. The proposed article included a sealed ampule which contained pressurized denicotinized smoke. An electric resistor was immersed in the smoke. In use, the terminals of the resistor were pushed into contact with a microbattery causing the resistor to generate heat and heat the smoke within the ampule. Draw by the user reportedly caused warm smoke to exit a valve near the mouthend of the article.
Japanese Patent Publication 8231/73 to Takeda proposed a cigar-shaped inhaler which included a battery powered Nichrome wire to heat air that, in turn, evaporated an essence from an essence container. The Nichrome wire was energized by either a manually-actuated or a draw actuated "on-off" switch.
West German Patent Application No. 2,653,133 to Kovacs proposed a smoking simulator having an internal battery which could accelerate or control the vaporization or emission of aromatic substances for delivery to the user. In supplemental West German Patent Application No. 2,704,218, Kovacs described the use of a vacuum or draw-actuated switch to switch "on" the battery operated heating coil.
A draw actuated, pressure transducer switch was described in U.S. Pat. No. 4,246,913 to Ogden et al, as part of a smoke aversion therapy article which delivered a small electrical shock to a smoker whenever the smoker drew on a cigarette.
U.S. Pat. No. 4,141,369 to Burruss proposed an article similar to the previously discussed McCormick articles. Burruss proposed a container which was electrically heated to a temperature sufficient to volatilize desired components from smoking material inserted therein. Heated air passing through the container during draw reportedly carried volatilized materials to the mouth of the user.
U.S. Pat. No. 4,303,083 to Burruss proposed a pipe having an electrical resistance heating element, a manually operated "on-off" power switch, and an opening above the resistance element for the addition of volatile compound. During use, the volatile compound was applied, using a squeeze tube or eye dropper, to a heated surface within the pipe, apparently on a puff-by-puff basis. The volatile compounds reportedly were vaporized, mixed with air drawn into the pipe, and inhaled by the user.
PCT Publication No. WO 86/02528 to Nilsson et al proposed an article similar to that described by McCormick. Nilsson et al proposed an article for releasing volatiles from a tobacco material which had been treated with an aqueous solution of sodium carbonate. The article resembled a cigarette holder and reportedly included a battery operated heating coil to heat an untipped cigarette inserted therein. A switch was activated to supply current to the heating coil. A temperature sensor reportedly disconnected and reconnected the battery in order to maintain the temperature generated by the device in a narrow temperature range. Air drawn through the device reportedly was subjected to elevated temperatures below the combustion temperature of tobacco and reportedly liberated tobacco flavors from the treated tobacco contained therein.
U.S Patent No. 4,735,217 to Gerth et al proposed a "cigarette-shaped" medicament dosing article having a pellet of vaporizable medicament and a Nichrome resistance heating element connected in series with a battery power source and a draw actuated switch. In their only working example, the Nichrome heating element allegedly achieved a temperature in the range of 190.degree. F. to 220.degree. F. (90.degree. C. to 105.degree. C.) within a two second puff, which apparently was sufficient to volatilize menthol from a menthol pellet. At Column 8, lines 43-63, Gerth et al. went on to speculate that their article could be used to vaporize nicotine from a nicotine-containing pellet and that they believed it feasible to coat the heating element with a nicotine-containing compound in lieu of using a vaporizable pellet.
However, it is believed that it would not be possible to coat a Nichrome heating element, of the type described by Gerth et al, with enough vaporizable liquid material to deliver sufficient volatile material to the user, over the 6 to 10 puff life of a typical cigarette. It also is believed that the article of Gerth et al would not be able to provide enough electrical energy to (i) vaporize volatile material until near the end of a typical two second puff, or (ii) provide a high enough temperature (e.g., 150.degree. C. to 350.degree. C.) to vaporize many volatile materials within a two second puff, including many desirable aerosol forming substances and most volatile tobacco flavor components. In addition, even with only a single AA battery, the article described by Gerth et al. is more than 3 times the diameter and many times heavier than a typical cigarette and is provided with a relatively imprecise draw actuated control switch and with no means of regulating the current or heat during the puff.
Despite many years of interest and effort, none of the foregoing articles employing electrical energy has ever realized any significant commercial success, and it is believed that none has ever been widely marketed. Moreover, it is believed that none of the foregoing electrical energy articles is capable of providing the user with the sensations of cigarette or pipe smoking.
Thus, it would be desirable to provide a smoking article which can provide the sensations of cigarette or pipe smoking, which does not burn tobacco or other material, and which does not produce combustion products.